JP2803716B2 - Radio channel controller in CDMA cellular system - Google Patents

Abstract

A radio channel control section 370 transmits and receives to and from an adjacent base station uplink/downlink channel communication qualities measured by a communication channel transmit/receive section 330 and a mobile station 410, respectively, compares them with predetermined lower and upper threshold values Tl/Th, requests a pilot channel transmit section 350 to decrease and increase the transmission power level of a pilot signal if the threshold value Tl is not reached and the threshold value Th is exceeded, respectively. For a downlink channel, a hand-off parameter is increased and decreased if the threshold value Tl is not reached and the threshold value Th is exceeded, respectively. For an uplink channel, the hand-off parameter is decreased and increased if the threshold value Tl is not reached and the threshold value Th is exceeded, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile station communicating with a base station located in each of a plurality of radio zones via a code division multiplexed radio channel based on a reception level of a pilot channel transmitted from the base station. In a mobile communication system adopting a CDMA (Code Division Multiple Access) system for selecting a base station, the present invention relates to a radio channel control device in a cellular system having a large number of small radio zones. The present invention relates to a radio channel controller in a CDMA cellular system that can secure a traffic processing capacity of the entire system.

[0002]

2. Description of the Related Art Conventionally, in this type of CDMA cellular system, a base station of each radio zone has a constant power level so as to keep its radio zone at a predetermined size so as to eliminate gaps between the radio zones. Is transmitting the pilot channel. For example, assuming that base stations are arranged at equal intervals, as shown in FIG. 15, each base station 111, 112, etc. transmits a pilot channel at the same power level. (Cell size) are equal. Each mobile station usually selects a base station in a higher-level radio zone, which is closer to the base station, based on the reception level of the pilot channel transmitted from the base station. Alternatively, a base station with which to communicate is selected in the boundary area of the wireless zone.

A conventional mobile communication system includes, for example, an automobile telephone system, and a plurality of mobile stations are multiple-accessed to a base station. Until now, this system has been based on frequency division multiple access (FDMA).
ple Access) and time division multiple access (TDMA: Ti
me Division Multiple Access) method was often used. However, recently, a code division multiple access (CDMA) system, which realizes multiple access by performing spread spectrum with a different spreading code for each channel, has attracted attention because of good frequency use efficiency.

However, a mobile communication system adopting the CDMA system has a feature that the quality of a communication channel gradually deteriorates as traffic increases. For this reason, if the traffic becomes excessive, the quality of communication drops below a required value, making it difficult to hear voice, and lowering the throughput of data communication.

Conventionally, a radio channel controller for a base station in a CDMA cellular system of this type solves such a problem, as shown in FIG. Control unit 102, traffic control unit 103, and traffic upper limit storage unit 1
04 is provided, and the traffic handled by each base station is limited to a predetermined value or less so that the communication quality does not decrease below a required value.

Here, the communication line control unit 101 controls a communication line such as assigning a wireless channel for communication with a mobile station in a wireless zone which is a communication range of the base station 100. It is connected to the wireless control unit 102 and the other is connected to the host controller, and is under the control of the traffic control unit 103. The wireless control unit 102 sets and connects a mobile station and a communication line via an antenna. The traffic control unit 103 stores a traffic allowable value that can maintain good communication quality in the own base station in the traffic upper limit storage unit 10.
4, the communication line control unit 101 is controlled so that the traffic handled by the communication line control unit 101 is suppressed to the traffic allowable value or less.

[0007] A technique for control based on the traffic amount is described in, for example, Japanese Patent Application Laid-Open No. 2-220526. This device utilizes the fact that the received power increases or decreases according to the traffic volume, estimates the traffic volume being handled by detecting the power of the radio signal received by the receiving means, and permits communication based on the result. By providing the control means for performing the prohibition and the prohibition, it is possible to achieve the object that the traffic volume to be handled can be suppressed to a certain value or less and the communication quality can be maintained to a required value or more.

Another technique is disclosed in, for example, Japanese Patent Laid-Open No. 5-1.
No. 45516. In this device, communication attributes (voice communication, facsimile communication, data communication, etc.) of a plurality of wireless terminals and an allowable traffic value for each communication attribute are stored, and the traffic of the accommodated wireless terminals is stored based on the stored contents of the memory. By controlling the traffic value to be equal to or less than the allowable traffic value, communication is not interrupted due to excessive traffic, so that the reliability is higher and the radio wave can be effectively used. The goal can be achieved.

[0009]

The above-described conventional CDM
In the radio channel controller in the A cellular system, each base station cannot handle traffic exceeding the allowable value set for each base station. On the other hand, each mobile station has a communicable area in the radio zone of each base station. Is constant, and the size of the radio zone of each base station is fixed. As a result, the mobile station concentrates in one radio zone, and a large number of calls are generated. When the base station in this radio zone restricts the traffic and the calling is prohibited, the mobile station is placed in the adjacent radio zone. Despite the fact that the base station in this wireless zone has a sufficient traffic processing capacity, the mobile station prohibited from making a call can not communicate, and the system as a whole can not communicate while there is enough traffic, that is, There is a problem that a state occurs in which the traffic processing capacity cannot be secured.

[0010] An object of the present invention is to provide a CDMA cellular system capable of expanding the traffic processing capacity of the entire system by processing part of this traffic in an adjacent radio zone even if traffic concentrates in one radio zone. To provide a wireless channel control device.

[0011]

According to a first aspect of the present invention, a radio channel controller in a CDMA cellular system communicates with a base station located in each of a plurality of radio zones via a code division multiplexed radio channel. In a radio channel controller in a CDMA cellular system in which a mobile station selects the base station based on a reception level of a pilot channel transmitted from the base station, the radio station controller is installed in the base station, and the uplink and downlink of its own station are provided. Quality measuring means for measuring at least one communication quality;
Power level control means for lowering the transmission power level of the pilot channel to a predetermined value when the measured value of the quality measurement means falls below a predetermined lower limit threshold value, the power level control means comprising: Exceeds the upper threshold of the predetermined quality, the transmission power level of the pilot channel is raised to a predetermined value.

With this configuration, the base station automatically lowers the transmission power level of the pilot channel and automatically changes the size of the radio zone (cell size) when the traffic volume processed by the base station increases and the communication quality deteriorates. On the other hand, when the traffic volume is reduced and the communication quality is increased, the transmission power level of the pilot channel is increased to automatically increase the size (cell size) of the wireless zone.

Further, the radio network controller notifies the transmission power level of the pilot channel to the adjacent base station and receives the transmission power level of the pilot channel of the adjacent base station from the adjacent base station. Level transmission / reception means, and the power level control means estimates the size of the wireless zone of the adjacent base station based on the transmission power level of the pilot channel notified from the adjacent base station, and The transmission power level of the pilot channel of the own station is adjusted and determined so that the wireless zone with the adjacent station overlaps.

With the addition of this configuration, the base station asks an adjacent station for traffic processing support when the size of the wireless zone of the base station is reduced, while the base station reduces the size of the wireless zone at the adjacent station. Expands its own wireless zone to support traffic processing, as well as gaps with adjacent wireless zones,
That is, occurrence of a non-sensing zone is prevented.

According to a second aspect of the present invention, in the radio channel controller, the reception level of a pilot channel received from a communicating base station is a predetermined handoff parameter T-DROP
For less than the target mobile station to disconnect the wireless channel with the base station in communication, is provided in the base station,
Quality measuring means for measuring the downlink communication quality of the own station;
When the measurement result of the quality measuring means interrupts a lower threshold of a predetermined quality, the quality measuring means further includes a handoff parameter controlling means for raising the handoff parameter T-DROP to a predetermined value, and the handoff parameter controlling means further comprises: If the measurement result exceeds the upper limit of the predetermined quality, the handoff parameter T-DROP is reduced to a predetermined value.

According to a third aspect of the present invention, in the radio channel controller, a reception level of a pilot channel received from a base station other than a base station which is not communicating is a predetermined handoff parameter TA.
Target mobile stations that start communication by connecting to a radio channel with a base station other than the one that is not communicating when DD is exceeded, and are installed in the base station and measure the communication quality of the downlink of an adjacent base station. Measuring means, and a hand-off parameter control means for increasing the hand-off parameter T-ADD to a predetermined value when the measurement result of the quality measuring means interrupts a lower threshold value of a predetermined quality. The control means reduces the handoff parameter T-ADD to a predetermined value when the measurement result exceeds a predetermined upper limit threshold of quality.

According to a fourth aspect of the present invention, in the radio channel control apparatus, the reception level of a pilot channel received from a communicating base station is a predetermined handoff parameter T-DROP
In the case where the reception level of the pilot channel received from the base station other than the currently communicating base station exceeds the predetermined handoff parameter T-ADD, the radio channel with the communicating base station is disconnected when the communication level is less than Targeting a mobile station that starts communication by connecting a radio channel with a base station other than the base station that is not performing communication, a quality measuring unit that is installed in the base station and measures the communication quality of the uplink of its own station; When the measurement result of the measuring means is below a lower threshold of a predetermined quality, the apparatus further includes a handoff parameter control means for lowering the handoff parameter T-DROP and the handoff parameter T-ADD to a predetermined value. When the measurement result exceeds a predetermined quality upper limit threshold value, the control means sets the handoff parameter T-D
The ROP and handoff parameter T-ADD are raised to predetermined values.

According to a fifth aspect of the present invention, in the radio channel controller, the reception level of the pilot channel received from the communicating base station is a predetermined handoff parameter T-DROP.
In the case where the reception level of the pilot channel received from the base station other than the currently communicating base station exceeds the predetermined handoff parameter T-ADD, the radio channel with the communicating base station is disconnected when the communication level is less than Targeting a mobile station that starts a communication by connecting a radio channel with a base station other than the base station that is not performing communication, a quality measuring unit that is installed in the base station and measures uplink communication quality of an adjacent base station; When the measurement result of the quality measuring means is below a lower threshold of a predetermined quality, the apparatus further includes a handoff parameter control means for lowering the handoff parameter T-DROP and the handoff parameter T-ADD to a predetermined value. When the measurement result exceeds a predetermined upper limit threshold of the quality, the parameter control means sets the handoff parameter T-DROP and And increasing the full parameter T-ADD to a predetermined value.

In the second to fifth aspects of the present invention, the base station raises or lowers the handoff parameter, thereby changing the reception level of the radio signal at the mobile station and relatively changing the base station. Since the size (cell size) of the wireless zone is changed, the traffic processing amount is appropriately adjusted, and the communication quality is maintained.

Further, the radio line control device according to the present invention comprises:
It has a configuration including at least one of the above five inventions.

Further, the radio channel control apparatus in the CDMA cellular system according to the above means,
When the communication quality is measured and the quality of the measurement result falls below a predetermined lower threshold, the traffic to be processed is reduced by reducing the cell size of the own station. If it exceeds, the traffic to be processed is taken in by increasing the cell size of the own station.

[0022]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a functional block diagram showing an embodiment of the present invention. The radio channel controller 10 in the CDMA cellular system shown in FIG. 1 includes an interface unit 11, a plurality of communication channel transmission / reception units 12, a control channel transmission / reception unit 13, a pilot channel transmission unit 14, a synchronization channel transmission unit 15, a radio channel control. Unit 16, transmitting unit 1
7, an antenna sharing unit 18 and a receiving unit 19, and can communicate with a plurality of mobile stations 20 via an antenna.

The CDMA cellular system to be applied is a US cellular system IS-95-A standard (Te
lecommunication Industry Association, TIA / EAI / IS-95
-A, "Mobile Station-Base Station Compatibility St
andard for Dual-Mode Wideband Spread Spectrum Celu
lar System ").

The present invention differs from the prior art in that the control channel transmitting / receiving section 13 can rewrite the handoff parameter in the mobile station, and the pilot channel transmitting section 14
, The transmission power level of the pilot channel can be raised and lowered, and the radio channel control unit 16 sets communication quality from the measured quality value, and based on the set communication quality, a handoff parameter to be transmitted to the mobile station 20 and By instructing to change at least one of the transmission power levels of the pilot channel, as shown in FIG. 14, the size of the wireless zone in which the mobile station 20 can communicate is increased or decreased.

The handoff parameters include a handoff parameter T-DROP and a handoff parameter T-ADD for setting a lower limit value and an upper limit value, respectively, at which a mobile station can receive a pilot channel from a base station.

The interface unit 11 transmits signals of the communication channel and the control channel transmitted and received by the communication channel transmitting / receiving unit 12 and the control channel transmitting / receiving unit 13, respectively, to an upper-level base station controller (Base Station Controller).
) (Not shown).

The communication channel transmission / reception section 12 spreads the downlink signal of the communication channel received from the interface section 11 into a spreading code unique to each channel, and then sends the spread signal to the transmission section 17 while transmitting the uplink signal received from the reception section 19 to each of the channels. A despreading process is performed using a spreading code unique to the communication channel, and an information signal before spreading is extracted and sent to the interface unit 11. Also,
The communication channel transmitting / receiving unit 12 periodically measures the quality (bit error rate, frame error rate) of the uplink signal, and
It reports to the radio channel control unit 16 along with the quality of the downlink signal transmitted periodically from 0.

The control channel transmitting / receiving section 13 spreads the downlink signal of the control channel received from the interface section 11 into a spreading code unique to each channel, and then sends the spread signal to the transmitting section 17, while transmitting the uplink signal of the control channel from the receiving section 19. A despreading process is performed using a spreading code specific to the receiving control channel, an information signal before spreading is extracted and sent to the interface unit 11, and the handoff parameter T-DROP and the handoff parameter T-ADD are transmitted to the mobile station on the downlink control channel. 2
Notifying to zero.

The hand-off parameter T-DROP and the hand-off parameter T-ADD are assumed to be rewritten upon receiving an instruction from the radio channel controller 16.

The pilot channel transmitting section 14 generates a pilot channel spread by a unique spreading code, and sends the pilot channel to the transmitting section 17 in addition to the spread downlink signal of the communication channel or control channel. It is assumed that the transmission power level of the pilot channel is notified to the radio channel controller 16. It is assumed that the transmission power level of the pilot channel can be changed up and down by a control signal received from the radio channel control unit 16. The pilot channel transmitted from the pilot channel transmitting unit 14 is always input to the dedicated pilot signal receiver of the mobile station 20, and the mobile station 20
Selects the base station with which to communicate by comparing the reception levels of the input pilot channels.

The synchronization channel transmitter 15 generates a synchronization channel spread by a unique spreading code, and sends the generated synchronization channel to the transmitter 17 in addition to the downlink signal of the communication channel or the control channel.

The radio channel controller 16 determines the quality of the uplink signal measured by the communication channel
0 and the quality of the downlink signal transmitted to the communication channel transmitting / receiving unit 12 and each report.
2, the average value, the median value, or the ratio of the measured value exceeding the required quality in each of the uplink signal and the downlink signal is calculated and set as the uplink communication quality and the downlink communication quality of the own base station. .

Further, the radio channel control unit 16 notifies the communication quality of the base station to the radio channel control units of a plurality of adjacent base stations via the interface unit 11 and the higher-level device, and also notifies each of the adjacent base stations of the communication quality. It is assumed that notification of the communication quality is received from the wireless channel control unit of each adjacent base station via the interface unit 11.

The radio channel controller 16 can instruct the control channel transmitter / receiver 13 according to the set communication quality to rewrite the handoff parameter.

Further, it is assumed that the radio channel controller 16 instructs the pilot channel transmitter 14 according to the set communication quality to change the transmission power level of the pilot channel up and down.

The radio channel control unit 16 notifies the radio channel control unit of each adjacent base station of the set transmission power level of the pilot channel via the interface unit 11 and the host device. It is assumed that the notification of the transmission power level of the pilot channel set by each station is received from the radio channel control unit of each adjacent base station via the interface unit 11.

The radio channel controller 16 estimates the shape of the radio zone of the adjacent base station from the received transmission power level of the pilot channel of the adjacent base station, the propagation loss model of the radio signal, the terrain information, and the like. It is assumed that the transmission power level of the pilot channel of the own base station that does not cause a gap (zone of signal insensitivity) between the zones is determined. Further, when estimating the shape of the wireless zone, the transmission power level of the pilot channel may be determined by obtaining only a rough cell radius by a propagation loss formula in order to simplify the control.

The transmission unit 17 is a communication channel transmission / reception unit 12
And a downlink signal output from each of the control channel transmitting and receiving unit 13 and added to the pilot channel and the synchronization channel as a digital signal, and after converting the analog signal into an analog signal, modulating the analog signal, frequency conversion to a radio frequency band, filtering, The signal is amplified and transmitted to the mobile station 20 via the antenna sharing unit 18.

On the other hand, from the mobile station 20 to the antenna sharing unit 18
The receiving unit 19, which receives an upstream signal via the CDMA, performs filtering, amplification, frequency conversion from a radio frequency signal to a baseband signal, demodulation of the input upstream signal of the analog signal, demodulation, and conversion into a digital signal. To the communication channel transmitting / receiving unit 12 and the control channel signal to the control channel transmitting / receiving unit 13.

Next, US IS-9 applied to the present invention.
The CDMA cellular system of the 5-A standard will be described. In this system, each base station continuously transmits a pilot channel spread by a unique spreading code, while a mobile station transmits one pilot signal from a plurality of neighboring base stations according to the reception levels of these pilot channels. It is assumed that communication is selected. Further, in the present invention, the reception level of the pilot channel received from the communicating base station by the mobile station is determined by the handoff parameter T-DROP
Is less than the base station, the communication with the communicating base station is disconnected, and the reception level of the pilot channel received from the base station other than the communicating base station is changed to the handoff parameter T-ADD.
If the number exceeds the limit, communication with a base station other than the one under communication is started.

Therefore, in such a CDMA cellular system, the cell size is changed by changing the transmission power level of the pilot channel up or down, or the handoff parameter is changed up and down, and the traffic of each base station is controlled. Thereby, good communication quality can be maintained.

Next, a case where the cell size is changed by changing the transmission power level of the pilot channel up and down according to the first invention will be described with reference to FIGS. 9 and 10.

FIG. 9 is an explanatory diagram showing which of the base station 1 and the base station 2 the mobile station that is waiting for requests connection.

A mobile station in standby (not shown) measures the reception level of the pilot channel of each base station, and requests connection to the base station having the highest reception level.
First, before the control of the cell size change, if the transmission power level of the pilot channel of the base station 12 is the same and the reception level of the pilot channel of the mobile station is a level diagram indicated by a broken line, the base station 1 and the base station 2 to be selected are selected. Is at waypoint K of the base station.

Now, when the traffic processing amount of the base station 1 approaches the allowable value and the deterioration of the communication quality of the base station 1 is detected,
If the transmission power level of the pilot channel of the base station 1 is lowered and the reception level of the pilot channel of the mobile station is lowered as shown by the solid line in the figure, the boundary line is
Side, and if left as it is, a gap is created in the wireless zone. In this state of the base station 1, when the communication quality of the adjacent base station 2 is excellent and exceeds a predetermined value, the base station 2 raises the transmission power level of the pilot channel, and the reception level of the pilot channel of the mobile station is illustrated. When raised like a solid line, the boundary line moves to the intersection J of the solid line to obtain an overlapping area portion.

That is, for a mobile station that is waiting,
The cell size of the base station 1 will decrease, while the cell size of the base station 2 will increase. As a result, in the base station 1, the margin for the thermal noise increases due to the decrease in the cell size, the allowable value of the traffic processing amount increases, and the traffic newly generated for the base station 1 decreases.

Further, even if the communication quality is degraded due to the large amount of traffic processed by one base station 1 and the cell size is reduced, the communication quality exceeding a predetermined level in another adjacent base station 2 or the like is not improved. In order to avoid the risk of creating a gap between the wireless zones when it cannot be obtained, the transmission power level of the pilot channel is reported between adjacent base stations.

Next, FIG. 10 is an explanatory diagram showing which of the base station 1 and the base station 2 the communicating mobile station can communicate with.

The mobile station during communication measures the reception level of the pilot channel of each base station, and when the reception levels of the pilot channels of a plurality of base stations exceed the required values, the mobile stations simultaneously transmit the plurality of base stations. Communication can be performed. Such a state is called soft handoff, and communication quality can be improved by a site diversity (Site Diversity) effect.

First, when the transmission power levels of the pilot channels of the two base stations 1 and 2 are substantially the same and the reception levels of the pilot channels of the mobile station are shown by broken lines, the mobile station is connected to the base station 1 and the base station. The soft handoff area in which communication with both stations 2 is possible is an area between the point F and the point H located almost in the middle of both base stations. Now, when the traffic of the base station 1 approaches the allowable value,
Is detected, the transmission power level of the pilot channel of the base station 1 is decreased, the transmission power level of the pilot channel of the base station 2 is increased, and the reception level of the pilot channel of the mobile station is shown. It changes to a solid line.

As a result, after the transmission power is controlled, the soft handoff area where the mobile station can communicate with both the base station 1 and the base station 2 moves to the base station 1 side. That is, the cell size of the base station 1 is reduced and the cell size of the base station 2 is increased even for a mobile station in communication. As a result, as described above, in the base station 1, the allowable value of the traffic processing amount increases, and the traffic processing amount accommodated in the base station 1 decreases.

Next, a case where the cell size is changed based on the hand-off parameter T-DROP according to the second invention will be described with reference to FIG. FIG.
Indicates that the mobile station 20 in soft handoff between the base station 1 and the base station 2 moves away from the base station 1 in communication.
FIG. 4 is an explanatory diagram showing a position where communication with the device is disconnected. The moving mobile station 20 has received the pilot channels of the base station 1 and the base station 2, and as shown in the drawing, the reception level of the pilot channel of the base station 1 during the soft handoff corresponds to the handoff parameter T-DROP. Point H no longer filled
Requesting the base station 1 to disconnect the communication.

On the other hand, since the mobile station 20 measures the communication quality of the downlink signal from the base station 1 during communication and notifies the base station 1 of the communication partner, the base station 1 measures the communication quality of the downlink. Raises the handoff parameter T-DROP of the base station 1 when the deterioration of the base station is known. As a result of this control, the position where the mobile station moving away from the base station 1 is disconnected moves to a point G on the base station 1 side.

This means that the number of mobile stations communicating with the base station 1 is reduced, and there is a margin in the transmission power of the base station 1 for the downlink. Distribution to channels can improve downlink communication quality. At this time, since the soft handoff area is reduced, the interference power for the uplink increases, and the communication quality of the uplink deteriorates accordingly.

Next, a case where the cell size is changed based on the upper and lower hand-off parameters T-ADD according to the third invention will be described with reference to FIG. FIG. 12 is an explanatory diagram showing a position where the mobile station 20 communicating only with the base station 2 between the base station 1 and the base station 2 approaches the base station 1 and connects the communication with the base station 1. The mobile station 20 during communication measures the reception level of the pilot channel of each base station, and when the reception level of the pilot channel of the base station other than the communication station exceeds the handoff parameter T-ADD, the base station that has exceeded the level is used. Request a connection with

When the communication quality of the downlink of the base station 1 is deteriorated, the handoff parameter T-ADD of the base station 2 is increased. Therefore, after this control, the base station 1
Moves from the point H before the control to the point G closer to the base station 1 side.

This means that the number of mobile stations communicating with the base station 1 decreases, and there is a margin in the transmission power of the base station 1 with respect to the downlink. Distribution to communication channels can improve the communication quality of the downlink. At this time, since the soft handoff area is reduced, the interference power for the uplink increases, and the communication quality of the uplink deteriorates accordingly.

Next, a case where the cell size is changed based on the change of the handoff parameter T-DROP and the handoff parameter T-ADD according to the fourth and fifth aspects will be described with reference to FIG. FIG. 13 shows the position of a mobile station (not shown) between base station 1 and base station 2,
FIG. 7 is an explanatory diagram showing a state where a base station as a communication partner of the mobile station changes. In the figure, the hand-off parameter T-DROP and the hand-off parameter T
-ADD is the same.

The mobile station during communication measures the reception level of the pilot channel of each base station, and when the reception level of the pilot channel of the base station other than that of the communication exceeds the handoff parameter T-ADD, the level is exceeded. Request connection with base station. Also, the reception level of the pilot channel of the base station during soft handoff is equal to the handoff parameter T-D.
When the ROP is no longer satisfied, the base station is requested to disconnect the communication.

Now, when the communication quality of the uplink of the base station 1 is degraded, the handoff parameters T-DROP and T
-Each ADD is lowered. Therefore, after this control, the soft hand-off area for communicating with both the base station 1 and the base station 2 extends from the points FG to the points E to H extending from the points FG to the base station 1 or the base station 2 as shown in the figure.
Changes to

This means that the proportion of mobile stations whose transmission power level has been reduced due to the site diversity effect of soft handoff increases, and thus the communication quality of the uplink is improved.
At this time, since the soft hand-off area increases, the interference power for the downlink increases, and the communication quality of the downlink deteriorates accordingly.

Next, a basic operation procedure of the radio channel controller 10 according to the present invention will be described with reference to FIG. 1 and FIG.

First, the radio channel controller 10 measures the predetermined location periodically, for example, every second by the radio channel controller 16, and calculates the measurement result to obtain the communication quality T.
Is set (step S1), and when the communication quality T interrupts without reaching the predetermined lower limit threshold value T1 (Y in step S2).
ES), an operation of reducing the cell size by a predetermined value is performed as described (step S3). Threshold Tl
Is, for example, 1% in communication quality with respect to the bit error rate,
The communication quality for the frame error rate is 3%, and the communication quality for the degradation rate is 5%.

If the communication quality T exceeds the threshold value Tl and further exceeds a predetermined upper threshold value Th (YES in step S4), if the procedure S2 is "NO", the radio line controller 1
0 performs an operation of expanding the cell size by a predetermined value (procedure S5). If the previous step S4 is "NO" and the communication quality T is between the threshold value Th and the threshold value Tl, no operation is performed. Here, the threshold value Th is predetermined such as 0.1% for the communication quality for the bit error rate, 0.3% for the communication quality for the frame error rate, and 0.5% for the communication quality for the deterioration rate. Have been.

Next, means and procedures in the first to fifth inventions for changing the cell size described with reference to FIG. 2 will be described with reference to the drawings.

First, with reference to FIG. 1 and FIG. 3, a procedure according to the first invention for changing the cell size by increasing or decreasing the transmission power level of the pilot channel will be described.

In the present invention, the radio line control device 10
The wireless channel control unit 16 periodically measures at least one of the downlink and uplink communication qualities of the base station and sets the communication quality T (step S11). Interruption without reaching Tl (procedure S
12), the pilot channel transmitting unit 14 is instructed to lower the transmission power level of the pilot channel by a predetermined value Al dB (for example, 1 dB) (step S13), so that the cell size of the own station is reduced by a predetermined value. Is shrinking.

If the procedure S12 is "NO" and the communication quality T exceeds the threshold value Tl and further exceeds the threshold value Th (YES in the procedure S14), the radio channel controller 16 sets the pilot channel to The transmission power level is set to a predetermined value Ah dB
By instructing the pilot channel transmission unit 14 to increase the frequency (for example, 1 dB) (step S15),
The cell size of the own station is expanded by a predetermined value. On the other hand, if the procedure S14 is "NO" and the communication quality T is between the threshold value Th and the threshold value Tl, no operation is performed.

Note that a lower limit value and an upper limit value are set in advance for the transmission power level of the pilot channel, and the transmission power level does not exceed this range.

Next, a procedure for checking the cell size of the adjacent base station and determining the cell size of the own base station will be described with reference to FIG. 1 and FIG.

First, the radio channel controller 16 of the radio channel controller 10 sets a parameter i (from 1 to N) for identifying N adjacent base stations to “i = 1” and sets the pilot of the own base station. Maximum transmission power level Pmax of the channel
Is set to "Pmax = 0" (step S21).

Next, the radio line control unit 16 determines that “i =
The transmission power level P (i =) 1 of the pilot channel of the 1 "th adjacent base station is obtained (step S22), and based on the transmission power level P1 of the pilot channel, as described above, the radio power of this adjacent base station is obtained. The zone S (i =) 1 is estimated (step S23).

Next, based on the estimated radio zone S1 of the adjacent base station, the radio channel control section 16 controls the transmission power level Pown of the pilot channel of the own base station so that no gap is formed between the radio zones of both base stations. Is determined (procedure S2
4) Compare with the previously set maximum transmission power level Pmax (= 0) of the pilot channel of the own base station (step S2).
5).

If the step S25 is "YES" and "Pown> Pma
x (= 0) ", the radio channel controller 16 sets the maximum transmission power level Pmax of the pilot channel of the base station to" Pow ".
n ”(step S26), and compares the parameter i (= 1) of the adjacent base station with the number N of stations (step S27).
If step S25 is "NO" and "Pown>Pmax" is not satisfied, the procedure skips step S26 and proceeds to step S27.

Step S27 is "YES" and "i = 1 <N"
In the case of, the wireless channel control unit 16 determines that the parameter (i =) 1
Is changed to parameter (i + 1 =) 2 (step S28), and the procedure returns to step S22, and the procedure is repeated until "i = N" and step S27 becomes "NO".

Next, referring to FIG. 1 and FIG. 5, a second invention in which the handoff parameter T-DROP is increased or decreased in accordance with the change of the downlink communication quality of the base station and the cell size is changed. The procedure will be described.

In the present invention, the radio line controller 10
The wireless channel control unit 16 periodically measures the downlink communication quality of the base station and sets the communication quality T (step S31).
If the communication quality T interrupts without reaching the threshold value Tl (YES in step S32), the handoff parameter TD
By instructing the control channel transmitting / receiving unit 13 to increase the ROP by a predetermined value Yl dB (for example, 1 dB) (step S33), the cell size of the mobile station is reduced by a predetermined value with respect to the mobile station.

If the procedure S32 is "NO" and the communication quality T exceeds the threshold value Tl and further exceeds the threshold value Th (YES in the procedure S34), the radio line controller 16 sets the handoff parameter T By instructing the control channel transmitting / receiving unit 13 to lower the -DROP by a predetermined value Yh dB (for example, 1 dB) (procedure S35), the cell size of the mobile station with respect to the mobile station is expanded by a predetermined value. If the previous step S34 is "NO" and the communication quality T is between the threshold value Th and the threshold value Tl, no operation is performed.

A lower limit and an upper limit are set in advance in the handoff parameter T-DROP, and the handoff parameter T-DROP exceeding this range is ignored by the control channel transmitting / receiving section 13 and transmitted to the mobile station. Never.

Next, referring to FIG. 1 and FIG. 6, a hand-off parameter T-ADD is increased or decreased in accordance with a change in downlink communication quality of an adjacent base station, and a cell size of the own base station is changed. The procedure according to the third invention will be described.

In the present invention, the radio line control device 10
The wireless channel control unit 16 periodically measures the downlink communication quality of the adjacent base station and sets the communication quality T (step S4).
1) If the communication quality T interrupts without reaching the threshold value Tl (YES in step S42), the control channel transmitting / receiving unit increases the handoff parameter T-ADD by a predetermined value Bl dB (for example, 1 dB). By instructing the mobile station 13 (procedure S43), the cell size of the adjacent station with respect to the mobile station is reduced by a predetermined value.

If the procedure S42 is "NO" and the communication quality T exceeds the threshold value Tl and further exceeds the threshold value Th (YES in the procedure S44), the radio line control section 16 sets the handoff parameter T -ADD is a predetermined value Bh dB (for example,
1 dB), the control channel transmitting / receiving unit 13
(Step S45), the cell size of the adjacent station with respect to the mobile station is increased by a predetermined value. If the previous step S44 is "NO" and the communication quality T is between the threshold value Th and the threshold value Tl, no operation is performed.

Note that a lower limit and an upper limit are set in advance in the handoff parameter T-ADD, and the handoff parameter T-ADD exceeding this range is ignored by the control channel transmitting / receiving section 13 and transmitted to the mobile station. Never.

Next, referring also to FIG. 7 and FIG. 7, the handoff parameter T-DROP and the handoff parameter T-ADD are raised and lowered according to the change in the communication quality of the uplink of the own base station, and the cell size is changed. The procedure according to the fourth invention will be described.

In the present invention, the radio line controller 10
The radio channel control unit 16 periodically measures the uplink communication quality of the base station and sets the communication quality T (step S51).
If the communication quality T interrupts without reaching the threshold value Tl (YES in step S52), the handoff parameter TD
ROP and handoff parameter T-ADD are set to a predetermined value Zld
By instructing the control channel transmitting / receiving unit 13 to decrease the cell size by B (for example, 1 dB) (procedure S53), the cell size of the mobile station is reduced by a predetermined value with respect to the mobile station.

If the procedure S52 is "NO" and the communication quality T exceeds the threshold value Tl and further exceeds the threshold value Th (YES in procedure S54), the radio line control unit 16 sets the handoff parameter T By instructing the control channel transmitting / receiving unit 13 to increase the -DROP and the handoff parameter T-ADD by a predetermined value Zh dB (for example, 1 dB) (procedure S55), the cell size of the mobile station with respect to the mobile station is increased by a predetermined value. It is expanding. The previous step S54 is "N
O ", the communication quality T is equal to the threshold value Th and the threshold value Tl.
No action takes place if they are between.

As described above, the handoff parameter TD
A lower limit value and an upper limit value are set in advance in the ROP and the handoff parameter T-ADD, and a handoff parameter exceeding this range is ignored by the control channel transmitting / receiving unit 13 and is not transmitted to the mobile station.

Next, referring to FIG. 1 and FIG. 8, the hand-off parameter T-DROP and the hand-off parameter T-ADD are increased and decreased in accordance with the change in the uplink communication quality of the adjacent base station, and A procedure according to the fifth invention for changing the cell size will be described.

In the present invention, the radio line control device 10
The wireless channel control unit 16 periodically measures the uplink communication quality of the adjacent base station and sets the communication quality T (step S6).
1) If the communication quality T interrupts without reaching the threshold value Tl (YES in step S62), the hand-off parameter T-DROP and the hand-off parameter T-ADD are reduced by a predetermined value Cl dB (for example, 1 dB). To the control channel transmitting / receiving unit 13 (step S63), thereby increasing the cell size of the mobile station by a predetermined value with respect to the mobile station.

If the procedure S62 is "NO" and the communication quality T exceeds the threshold value Tl and further exceeds the threshold value Th (YES in the procedure S64), the radio line controller 16 sets the handoff parameter T By instructing the control channel transceiver 13 to increase the -DROP and the handoff parameter T-ADD by a predetermined value Ch dB (for example, 1 dB) (procedure S65), the cell size of the mobile station with respect to the mobile station is increased by a predetermined value. Is shrinking. The previous step S64 is "N
O ", the communication quality T is equal to the threshold value Th and the threshold value Tl.
No action takes place if they are between.

As described above, the handoff parameter TD
A lower limit value and an upper limit value are set in advance in the ROP and the handoff parameter T-ADD, and a handoff parameter exceeding this range is ignored by the control channel transmitting / receiving unit 13 and is not transmitted to the mobile station.

Note that a lower limit value and an upper limit value are set in advance for the handoff parameter T-ADD, and the handoff parameter T-ADD exceeding this range is ignored by the control channel transmitting / receiving section 13 and transmitted to the mobile station. Never.

In the above description, the radio channel controller is provided in the base station. However, the radio channel controller may be provided in a controller in a higher network.

In the above description, the communication quality is measured at regular intervals of one second. However, the measurement timing is arbitrary and is not limited to the above description. Similarly, the functional blocks and the operation procedure have been illustrated and described, but the allocation and separation of functions and the movement before and after the procedure are free. That is, changes may be made freely within a range satisfying the above functions, and the above description does not limit the present invention.

[0096]

As described above, according to the present invention, the transmission power level of the pilot channel is set at the base station side in accordance with the deterioration of the communication quality of each of the uplink and downlink at the own base station and the adjacent base station. Is obtained. With this configuration, in the base station, when traffic increases and communication quality deteriorates, the cell size is reduced, so that the traffic margin for thermal noise increases and the capacity to accommodate traffic can be increased.

Further, the transmission power level of the pilot channel is notified between adjacent base stations, and the size (cell size) of each radio zone is estimated to adjust the transmission power level of the pilot channel in each base station. A radio channel controller is obtained. With this configuration, when the traffic increases and the communication quality deteriorates, the base station can increase the cell size of the adjacent base station, so that the traffic included in the wireless zone of the base station whose traffic has increased can be replaced by the adjacent base station. Can be distributed to stations.

Also, as the communication quality increases,
A radio channel controller for increasing the transmission power level of the pilot channel is obtained. With this configuration, the base station:
When the traffic decreases and the communication quality increases, the cell size increases, so that the traffic included in the wireless zone of the base station whose traffic has increased can be distributed to adjacent base stations.

Further, when the downlink is deteriorated, a radio channel control device which increases the hand-off parameter T-DROP and the hand-off parameter T-ADD for the communicating mobile station is obtained. With this configuration, the number of communicating mobile stations is reduced, and a margin is generated in the downlink transmission power. By distributing this margin to the downlink communication channel in use, the communication quality of the downlink is improved, and Downstream communication quality can be balanced.

Further, when the uplink is degraded, a radio channel control device that lowers the hand-off parameter T-DROP and the hand-off parameter T-ADD for the communicating mobile station is obtained. With this configuration, the soft hand-off area is expanded, and by increasing the proportion of mobile stations whose transmission power level is reduced by the diversity effect, the communication quality of the uplink is improved, and the communication quality of the uplink and downlink is balanced. be able to.

As a result, by changing the transmission power level of the pilot channel up or down or by changing the handoff parameter up or down, the cell size changes and the traffic of each base station is controlled, thereby improving the communication quality. It can be maintained well.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a basic procedure for implementing the present invention.

FIG. 3 is a flowchart showing a procedure according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a procedure associated with FIG. 3;

FIG. 5 is a flowchart showing a procedure according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing a procedure according to a third embodiment of the present invention.

FIG. 7 is a flowchart showing a procedure according to a fourth embodiment of the present invention.

FIG. 8 is a flowchart showing a procedure according to a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an example of a connection request range according to a change in transmission power level of a pilot channel.

FIG. 10 is an explanatory diagram showing an example of a communicable range accompanying FIG. 9;

FIG. 11 is an explanatory diagram showing an example of a cell size change accompanying a change in a handoff parameter T-DROP.

FIG. 12 is an explanatory diagram showing an example of a cell size change accompanying a change in a handoff parameter T-ADD.

FIG. 13 is an explanatory diagram illustrating an example of a cell size change accompanying a change in a handoff parameter T-DROP and a handoff parameter T-ADD.

FIG. 14 is an explanatory diagram showing an example of a cell size change.

FIG. 15 is an explanatory diagram showing an example of a conventional fixed cell size.

FIG. 16 is a functional block diagram showing an example of the related art.

[Description of Signs] 10 Radio channel control device 11 Interface unit 12 Communication channel transmission / reception unit 13 Control channel transmission / reception unit 14 Pilot channel transmission unit 15 Synchronization channel transmission unit 16 Radio channel control unit 17 Transmission unit 18 Antenna sharing unit 19 Receiving unit 20 Move Station

Claims (12)

(57) [Claims] 1. A mobile station communicating with a base station located in each of a plurality of radio zones by a code division multiplexed radio channel selects the base station based on a reception level of a pilot channel transmitted from the base station. CDM to do
In a radio channel controller in an A cellular system, a quality measuring unit provided in the base station for measuring communication quality of at least one of an uplink and a downlink of the own station, and a measured value of the quality measuring unit is a predetermined quality. A radio channel controller in a CDMA cellular system, comprising: power level control means for lowering a transmission power level of the pilot channel to a predetermined value when a lower limit threshold value is interrupted. 2. The power level control means according to claim 1, wherein said power level control means raises the transmission power level of said pilot channel to a predetermined value when said measurement result exceeds a predetermined quality upper limit threshold value. Wireless channel control device in a CDMA cellular system. 3. The transmission according to claim 1, wherein the transmission power level of the pilot channel is notified to an adjacent base station and the transmission power level of the pilot channel of the adjacent base station is notified from the adjacent base station. Power level transmitting and receiving means, the power level control means,
Estimating the size of the wireless zone of the adjacent base station based on the transmission power level of the pilot channel notified from the adjacent base station, and transmitting the pilot channel of the own station so that the wireless zones of the own station and the adjacent station overlap. A radio channel controller in a CDMA cellular system, wherein the radio channel controller adjusts and determines a power level. 4. A mobile station communicating with a base station located in each of a plurality of radio zones by a code division multiplexed radio channel selects the base station based on a reception level of a pilot channel transmitted from the base station. CDM to do
In a radio channel controller in an A cellular system, when a reception level of a pilot channel received from a communicating base station is less than a predetermined hand-off parameter T-DROP, the mobile station disconnects a radio channel with the communicating base station. A quality measuring means provided for the station and installed in the base station for measuring the downlink communication quality of the own station, and the handoff when the measurement result of the quality measuring means is below a lower limit of a predetermined quality. A radio channel controller in a CDMA cellular system, comprising: a handoff parameter controller for increasing a parameter T-DROP to a predetermined value. 5. The hand-off parameter T-D according to claim 4, wherein said hand-off parameter control means determines that said hand-off parameter T-D when said measurement result exceeds a predetermined quality upper limit threshold.
A radio channel controller in a CDMA cellular system, wherein ROP is reduced to a predetermined value. 6. A mobile station communicating with a base station located in each of a plurality of radio zones by a code division multiplexed radio channel selects the base station based on a reception level of a pilot channel transmitted from the base station. CDM to do
In a radio channel controller in an A cellular system, when a reception level of a pilot channel received from a non-communicating base station exceeds a predetermined handoff parameter T-ADD, a radio channel with the non-communicating base station is connected. A quality measuring means for measuring a communication quality of a downlink of an adjacent base station, the quality measuring means being provided in the base station, and a measurement result of the quality measuring means being a threshold of a lower limit of a predetermined quality. And a handoff parameter control means for increasing the handoff parameter T-ADD to a predetermined value when interrupting the value. 7. The handoff parameter T-A according to claim 6, wherein the handoff parameter control means is configured to control the handoff parameter TA when the measurement result exceeds a predetermined upper limit threshold of quality.
A radio channel controller in a CDMA cellular system, wherein DD is reduced to a predetermined value. 8. A mobile station communicating with a base station arranged in each of a plurality of radio zones by a code division multiplexed radio channel selects the base station based on a reception level of a pilot channel transmitted from the base station. CDM to do
In a radio channel controller in an A cellular system, when a reception level of a pilot channel received from a communicating base station is less than a predetermined handoff parameter T-DROP, a radio channel with the communicating base station is disconnected. The communication is stopped, and when the reception level of the pilot channel received from the base station other than the communicating base station exceeds a predetermined handoff parameter T-ADD, the wireless channel with the base station other than the communicating base station is connected to start the communication. Targeting a mobile station, installed in the base station, and a quality measuring means for measuring the uplink communication quality of its own station, when the measurement result of the quality measuring means is below the lower threshold of the predetermined quality, And a handoff parameter control means for lowering the handoff parameter T-DROP and the handoff parameter T-ADD to predetermined values. The radio network controller in a CDMA cellular system to. 9. The method according to claim 8, wherein the hand-off parameter control means is configured to control the hand-off parameter T-D if the measurement result exceeds a predetermined quality upper limit threshold.
A radio channel controller in a CDMA cellular system, wherein a ROP and a handoff parameter T-ADD are raised to predetermined values. 10. A mobile station communicating with a base station located in each of a plurality of radio zones by a code division multiplexed radio channel selects the base station based on a reception level of a pilot channel transmitted from the base station. CD to do
In a radio channel controller in an MA cellular system, when a reception level of a pilot channel received from a communicating base station is less than a predetermined handoff parameter T-DROP, a radio channel with the communicating base station is disconnected. The communication is stopped, and when the reception level of the pilot channel received from the base station other than the communicating base station exceeds a predetermined handoff parameter T-ADD, the wireless channel with the base station other than the communicating base station is connected to start the communication. For a mobile station, provided in the base station, a quality measuring means for measuring the communication quality of the uplink of the adjacent base station, and when the measurement result of the quality measuring means is below a lower threshold of a predetermined quality, A handoff parameter control means for reducing the handoff parameter T-DROP and the handoff parameter T-ADD to a predetermined value. The radio network controller in a CDMA cellular system characterized by and. 11. The hand-off parameter control unit according to claim 10, wherein the hand-off parameter control unit determines that the hand-off parameter T-D is set when the measurement result exceeds a predetermined upper limit threshold of quality.
A radio channel controller in a CDMA cellular system, wherein a ROP and a handoff parameter T-ADD are raised to predetermined values. 12. A radio channel control apparatus in a CDMA cellular system, comprising at least two of the first to eleventh aspects.